!X.TITLE='LOG!i10!n ( Intensity / kR )'
!y.title='LOG!i10!n ( Exposure Time / s )'
!p.title='LOG!i10!n ( Signal-to-Noise Ratio for PoCa CCD Camera )'
contour,alog10(ratio(*,*,0)),alog10(src),alog10(texp),/follow,levels=lev
IDL> xyouts,-.8,-.85,'Dark current = 5 e!e-!n/s  Gain = 0.215 DN/e!e-!n
Read noise = 15 e!e-!n'
IDL> xyouts,-.8,2.2,'Sensitivity = 8 e!e-!n/kR/s/pixel  No binning'
 print,sens
      8.00000      10.0000      12.0000      14.0000      16.0000
18.0000      20.0000
IDL>
print,src
     0.100000     0.200000     0.400000     0.800000      1.60000
3.20000      6.40000
      12.8000      25.6000      51.2000
 print,texp
     0.200000     0.400000     0.800000      1.60000      3.20000
6.40000      12.8000
      25.6000      51.2000      102.400